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• movenc : Adjust edit lists to trim out parts of tracks with negative pts

  29 septembre 2012, par Michael Niedermayer

  movenc : Adjust edit lists to trim out parts of tracks with negative pts
  This makes sure that audio preroll for e.g. AAC is signaled correctly.
  Previously we only wrote the edit list correctly if we had negative
  
  dts but started with pts == 0 (e.g. for video with B-frames).
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavformat/movenc.c

• FFMPEG, change default audio track with code

  2 août 2019, par Gralex

  I have mkv video, and what just change default audio track without remux, encode/decode and other stuff. How it can be done with code ?

  AVFormatContext *pFormatCtx;
  
  
  
  av_register_all();
  
  avcodec_register_all();
  
  avformat_network_init();
  
  pFormatCtx = avformat_alloc_context();
  
  
  
  if (avformat_open_input(&pFormatCtx, [videoPath UTF8String], NULL, NULL) != 0) {
  
      avformat_close_input(&pFormatCtx);
  
      return;
  
  }
  
  
  
  if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
  
      avformat_close_input(&pFormatCtx);
  
      return;
  
  }
  
  
  
  for (int i = 0; i < pFormatCtx->nb_streams; i++) {
  
      if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
  
          // so we have audio track info
  
          // what todo next?
  
      }
  
  }
  
  avformat_close_input(&pFormatCtx);

• Mute parts of Wave file using Python/FFMPEG/Pydub

  20 avril 2020, par Adil Azeem

  I am new to Python, please bear with me. I have been able to get so far with the help of Google/StackOverflow and youtube :). So I have a long (2 hours) *.wav file. I want to mute certain parts of that file. I have all of those [start], [stop] timestamps in the "Timestamps.txt" file in seconds. Like this :

  



     0001.000 0003.000
   0744.096 0747.096
   0749.003 0750.653
   0750.934 0753.170
   0753.210 0754.990
   0756.075 0759.075
   0760.096 0763.096
   0810.016 0811.016
   0815.849 0816.849


  



  What I have been able to do is read the file and isolate each tuple. I have just output the first tuple and printed it to check if everything looks good. It seems that the isolation of tuple works :) I plan to count the number of tuples (which is 674 in this case) and put in a 'for loop' according to that count and change the start and stop time according to the tuple. Perform the loop on that single *.wav file and output on file with muted sections as the timestamps. I have no idea how to implement my thinking with FFMPEG or any other utility in Python e.g pydub. Please help me.

  



     with open('Timestamps.txt') as f:
   data = [line.split() for line in f.readlines()]
   out = [(float(k), float(v)) for k, v in data]

   r = out[0] 
   x= r[0]
   y= r[1]
   #specific x and y values
   print(x)
   print(y)